Method of laying pipe sections

ABSTRACT

Joint for telescoping pipe sections including aligned recesses in both sections, sealing gaskets spaced apart from both edges of the recesses and compressed against both pipe sections, and solidifiable grout filling the recesses and all space between the sealing gaskets. A method of laying pipe sections underground and sealing the pipe joints from above ground.

This is a divisional of co-pending application Ser. No. 06/698,020 filedon Feb. 4, 1985, now U.S. Pat. No. 4,647,080.

BACKGROUND OF THE INVENTION

Large diameter pipe is normally laid in sections that are joinedtogether by means other than threaded joints. A typical system involvespipe sections having a spigot on one end and a bell on the other end.The spigot of one section is designed to telescope into the bell of thenext adjoining section and the space between the bell and the spigot isfilled with packing to prevent any leaks and contain the fluid to becarried in the pipe. Usually such pipe is laid in trenches, assembledand sealed in the trench, and then the trench is back filled with earth.Many problems have developed with such piping, which may be concrete,metal, plastic, or a combination of these. The packing and sealingusually is done by hand with the result that no two joints are assembledin exactly the same way, and they, therefore, have different strengthsand weaknesses. Furthermore, the shifting and settling of the earthproduces stresses that the joint cannot absorb. The use of cement groutproduces a brittle joint that cracks under minor flexural stress andadheres to the precast pipe only with great difficulty. The slightestlongitudinal stress easily produces cracks and fractures of the grout,particularly along the interface of the grout and the precast pipesection.

In more recent times there have been improvements suggested such as thatof U.S. Pat. No. 4,226,444 to Bunyan in which two straight pipe sectionsare abutted with a sleeve encircling the butt joint. The sleeve issealed at each end with an inflatable ring and the space between therings is filled with an epoxy resin which is allowed to harden underpressure. The resulting joint depends on a thin cylindrical film ofepoxy resin which readily breaks at the pipe interface when the pipesections are placed under tensile and flexural stresses.

It is an object of this invention to provide a novel improved pipejoint. It is another object of this invention to provide abell-and-spigot pipe joint having a keyway to be filled with grout.Still another object is to provide a method of laying an undergroundpipeline and sealing it after the pipeline has been covered with earthand stabilized. Other objects will appear from the more detaileddescription which follows.

BRIEF DESCRIPTION OF THE INVENTION

This invention relates to a pipe joint in which an inner pipe section istelescoped into an outer pipe section, which comprises a broadcircumferential recess in the outer surface of the inner pipe sectionand two narrow circumferential grooves, each spaced respectively apartfrom each edge of the recess, a compressible resilient ring sealinggasket in each of said grooves, and in compressive contact with theinside surface of the outer section, a broad circumferential recess onthe inside surface of the outer section positioned to be in alignmentwith the recess of the inner section when the sections are telescoped totheir joined position, the edges of both recesses being angularlydisposed with respect to the inside surface of the outer section and theoutside surface of the inner section, two diametrically opposedpassageways through the outer section from the outside surface to thebottom of the recess and a fluid solififiable grout filling all of thevolume of the recesses, the two passageways, and the remaining spacebetween the inner and outer sections and the two gaskets.

This invention also relates to a method of laying, testing, andassembling sections of pipe into an indefinite length of piping whichcomprises the sequential steps of:

(1) positioning an inner pipe section and an outer pipe section ingeneral longitudinal alignment for joining by telescoping the twosections together, the two sections when joined having alignedcircumferential recesses in their facing surfaces adjacent thetelescoping ends, and the inner section having a pair of circumferentialgrooves spaced on opposite ends of the recess;

(2) placing two spaced ring sealing gaskets around the inner sectionrespectively in the grooves;

(3) telescoping the inner section with gaskets in the grooves into theouter section to a predetermined depth;

(4) attaching two conduits to the recesses by two respective passagewaysthrough the outer section at generally vertically diametrically oppositepositions;

(5) pressurizing the space between the sealing gaskets by closing oneconduit and introducing a fluid under superatmospheric pressure into theother conduit to test the sealing capabilities of the gaskets in theassembled joint;

(6) introducing a solidifiable fluid grout through the conduit attachedto the lower passageway until the recess is filled with grout andsubstantially no air bubbles are present; and

(7) allowing the grout to solidify.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed to be characteristic of this invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation,together with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings in which:

FIG. 1 is a cross sectional view of one embodiment of the pipe joint ofthis invention.

FIG. 2 is a partial cross sectional view of a second embodiment of thepipe joint of this invention.

FIG. 3 is a partial cross sectional view of a third embodiment of thepipe joint of this invention.

FIG. 4 is a schematic view of a method of laying an underground pipeline in accordance with this invention.

DETAILED DESCRIPTION OF THIS INVENTION

In FIGS. 1-3 there is shown the details of the pipe joint of thisinvention. Each pipe section of a continuous pipe line is fashioned atits two ends to fit with an adjoining pipe section to produce amale-female telescopic joint. Such a joint is commonly known as abell-and-spigot joint, the bell being the female component and thespigot being the male component. For convenience in manufacture andassembly each pipe section has the male component (spigot) on one endand the female component (bell) on the other end. Pipe sections withbell-and-spigot joints are available in virtually all sizes of pipe, butare very common in sizes of 4 inches and larger. The pipe may be made ofany material, e.g., cast iron, cement, plastic, etc., and normally ismanufactured by molding techniques.

The critical part of the assembly of large diameter pipe lines is themaking of each joint so it will retain its sealing properties eventhough the joint may be subjected to stresses caused by settling of theearth where the pipe is laid or by tensile forces in the generaldirection of the axis of the pipe. In FIG. 1 there is shown the bell 10of one pipe section and spigot 11 of the next adjoining pipe sectiontelescoped together to make a pipe joint. The joint is sealed with tworing seal gaskets 14 and 15 which are retained, respectively, in forwardseal groove 12 and rearward seal groove 13 and which are compressedagainst the inside sealing surface 23 of bell 10. Gaskets 14 and 15 arespeced apart in the longitudinal direction along the axis of the pipe.Between gaskets 14 and 15 is a space 22 filled with grout that adheresto bell 10 and to spigot 11. Space 22 is annular in form and is producedby the combination of a circumferential recess 17 in the inner surfaceof bell 10, and the allowance between the outside surface of spigot 11and the inside surface of bell 10. In order to provide access to space22 an upper passageway 18 and a lower passageway 19 communicates throughthe wall of bell 10. Space 22 is filled with an adhesive grout as thefinal step in producing a strong nonrotatable joint. It is generallyconvenient to tap passageways 18 and 19 at 20 and 21, respectively, soas to provide a means for attaching a pipe nipple through which groutmay be introduced into space 22.

The shape of space 22 is important in producing a joint that is stronglyresistant to longitudinal stresses. This is due to the fact that thesolidified grout in space 22 acts like a mechanical key in resistingaxial movement of the pipe sections. Furthermore, the solidified groutcannot rotate in space 22 which is a common cause of failure in priorart joints. Among the important shape features is one involved in theassembly of spigot 11 into bell 10. As spigot 11 enters bell 10 there isthe possibility that forward ring seal gasket 14 will slip out of groove12, even though a lubricant may be employed on the inside surface ofbell 10 and on gasket 14 to reduce friction therebetween. It has beenfound advantageous to shape recess 17 along its rearward edge with aconical tapered surface 24 which helps to keep gasket 14 in groove 12.Angle B may be about 10°-30°, although it is preferred to be about 20°.It is, of course, important for gaskets 14 and 15 to be properly seatedin order to provide a pressure tight, leak-proof seal.

Another portion of space 22 which must be shaped in a special way toprovide extra strength to the pipe joint is surface 25 which is thebottom surface of the recess or depression 16 in inner spigot section11. This surface is sloped at an angle A which is from about 2° to about10°, preferably about 5°. The slope as may be seen in FIG. 1 is suchthat space 22 is thicker (radially from the axis of the pipe) at the endnear rearward ring seal gasket 15 than at the end near forware ring sealgasket 14. This shape provides a resistance to the tensile stresses thatmay be present tending to pull apart the two joined pipe sections. Thespace 22 is wedge-shaped similar to a mechanical key, which opposes allforces tending to pull spigot 11 out of bell 10. Any force tending tomove spigot 11 to the left in FIG. 1 causes a tightening of surface 25against the grout in space 22 and a resistance to any movement of spigot11 to the left. Similarly, forces tending to move spigot 11 to the right(deeper into bell 10) are resisted by the wedging action againstinclined surface 24. Thus the shape of space 22 helps to provide astrong, immovable joint. While FIG. 1 shows surface 25 to be sloped toproduce the wedge shape it is entirely suitable to slope bottom surface48 of recess or depression 17 in outer bell section 10 to obtain thedesired wedge shape, regardless of whether surface 25 is sloped or not.

In a test of a joint as shown in FIG. 1 against a joint where angles Aand B were 0° (i.e. where space 22 was essentially rectangular in crosssection) where all other characteristics were identical, the joint ofFIG. 1 withstood internal test pressures of approximately three timesthat of the prior art joint before structural failure occurred. The testinvolves preparing the joint, capping the pipe sections on both sides ofthe joint to form a test cylinder, and introducing fluid underincreasing pressure to the inside of the cylinder until the joint fails.Such a test produces both hoop and axial tensile stresses on the jointunder conditions similar to those expected to be encountered in actualusage.

In FIG. 2 there is shown a portion of a second embodiment of the pipejoint wherein space 22 is different from that of FIG. 1. Otherwise bothjoints are identical. In FIG. 2 space 22 is shaped with a double wedgecontour or butterly shape. The thickness of space 22 in a radialdirection and midway between edges 31 is less than the thickness at eachof edges 31. Angles C are from about 2° to about 10°, preferably about5°. Surface 30 inclines from a high point adjacent passageway 18 to lowpoints (deeper into the wall of spigot 11) at edges 31. In the samefashion, surface 28 inclines from a high point near passageway 18 to alow point (deeper into the wall of bell 10) at edge 31. The rearwardportion of recess 26, adjacent ring seal gasket 14, is sloped at surface29 to help maintain gasket 14 in groove 12 when assembling the joint.Surface 29 slopes at an angle D of about 10° to about 30°, preferablyabout 20°. This shape of space 22 provides for a double wedging actionto resist movement of spigot 11 longitudinally in either direction withrespect to bell 10.

In FIG. 3 there is shown a third embodiment of the pipe joint of thisinvention, the differences being found solely in the shape of space 22.In this instance, space 22 has a double wedge or butterfly shapegenerally similar to that shown in FIG. 2 except that edges 37 in FIG. 3are not as sharply angled from surfaces 34 and 36 as are the comparablecomponents in FIG. 2 where edges 31 are almost at right angles withsurfaces 28 and 30. It is well known that in stress analysis of shapes,sharp corners (as at the corner of edge 31 and surface 30 in FIG. 2) areplaces where fractures begin to occur when stresses reach a levelapproaching the failure limit of the structure. For this reason manystructures are designed to eliminate such sharp corners. The design ofFIG. 3 does exactly that. Angles E are from about 2° to about 10°,preferably 5°. Surface 35 is inclined at an angle F, about 10° to about30°, preferably about 20°, to facilitate assembly of spigot 11 into bell10 while keeping gasket 14 properly seated in groove 12.

In FIG. 4 there is an illustration of the method of laying pipe inaccordance with this invention. The illustration shows the laying ofpipe underground, although it is to be understood that the method issimilarly operable when the pipe is not covered or is above groundlevel. Pipe sections 38 are assembled and made ready to be joined,spigot to bell in the desired location. Sealing gaskets are placed inthe grooves of each spigot (see grooves 12 and 13 and gaskets 14 and 15in FIG. 1). The inside surface of each bell, the outside surface of eachspigot, and the gaskets are coated with a suitable lubricant and sizingmaterial. This material not only facilitates the assembly of the spigotand gaskets into the bell without displacing or disrupting the gasketsfrom their proper seating in their respective grooves, but also preparesthe surfaces of space 22 and the adjoining facing surfaces of spigot 11and bell 10 to be receptive to a grout that fills space 22. Thelubricant makes these surfaces more adherent to the grout. The spigotand its gaskets properly lubricated is then inserted into the bell tothe appropriate depth. Tubes 40 and 41 are then attached to upperpassageway 18 and lower passageway 19, respectively. The joint is thentested by pressurizing the annular space between sealing gaskets 14 and15 using tubes 40 and 41 as access conduits for the pressurized fluid.If no pressure drop of the pressurizing fluid occurs, after a requiredtime, the seal is considered to be tight. Earth is then backfilled intothe trench where the pipe is laid, taking care to keep tubes 40 and 41attached to passageways 18 and 19 with the upper ends 47 of tubes 40 and41 accessible above ground level 42. A grout sump 43 is connected totube 41 and a vacuum pump 44 is connected to tube 40. Grout isintroduced through tube 41 into passageway 19 while air is sucked out ofpassageway 18 through tube 40 until space 22 is filled with grout. Tubes40 and 41 are then cut and left under the ground level 42 as at 46 whilesump 43 and pump 44 move on to the next pair of tubes 40 and 41 (as at47) to fill the grout space of the next joint, and so on until theentire pipe line is completed.

For a fiber glass reinforced vinylester plastic pipe a suitable grout isa vinylester resin with or without a filler. A preferred combination isa mixture of 70% Derakane 470 (vinylester resin made and sold by DowChemical Company) and 30% miniature hollow glass balloons (about0.001-0.005 inch in diameter). A preferred lubricant and sizing materialfor this type of grout is Derakane XD 8084.03 primer (made and sold byDow Chemical Company).

While the invention has been described with respect to certain specificembodiments, it will be appreciated that many modifications and changesmay be made by those skilled in the art without departing from thespirit of the invention. It is intended, therefore, by the appendedclaims to cover all such modifications and changes as fall within thetrue spirit and scope of the invention.

What is claimed as new and what is desired to secure by Letters Patentof the United States is:
 1. A method of laying, testing, and assemblingsections of pipe into an indefinite length of piping which comprises thesequential steps of:(1) positioning an inner pipe section and an outerpipe section in general longitudinal alignment for joining bytelescoping the two sections together, the two sections when joinedhaving aligned circumferential recesses in their facing surfacesadjacent the telescoping ends, and the inner section having a pair ofcircumferential grooves spaced on opposite ends of the recess; (2)placing two spaced ring sealing gaskets around the inner sectionrespectively in the grooves; (3) telescoping the inner section withgaskets in the grooves into the outer section to a predetermined depth;(4) attaching two conduits to the recesses by two respective passagewaysthrough the outer section at generally vertically diametrically oppositepositions; (5) pressurizing the space between the sealing gaskets byclosing one conduit and introducing a fluid under superatmosphericpressure into the other conduit to test the sealing capabilities of thegaskets in the assembled joint; (6) covering the joined pipe sectionswtih earth and allowing the sections to settle and extending theconduits from the pipe sections to above ground level; (7) thereafterintroducing a solidifiable fluid grout through the conduit attached tothe lower passageway until the recess is filled with grout andsubstantially no air bubbles are present; and (8) allowing the grout tosolidify.
 2. The method of claim 1 wherein step (7) additionallyincludes applying a vacuum to the conduit attached to the upperpassageway while grout is introduced through the lower passagway.
 3. Themethod of claim 1 further comprising the step of (9) repressurizing thespace between the sealing gaskets by closing one conduit and introducinga fluid under superatmospheric pressure into the other conduit to testthe sealing capabilities of the gaskets in the assembled joint afterstep (6) and before step (7).
 4. The method of claim 1 wherein step (2)includes coating the sealing gaskets and the inside surface of the bellsection with a lubricant.
 5. The method of claim 1 wherein step (1)includes forming the edges of the recesses at an angle with respect tothe adjacent inside or outside surface of the respective outer and innersections.
 6. The method of claim 1 wherein step (1) includes forming atleast one circumferential recess to have a cross section, as seen on aplane containing the axis of the pipe section, which is wedge shapedwith its thickest dimension adjacent the end of the inner section andits thinnest dimension adjacent the end of the outer section.
 7. Themethod of claim 1 wherein step (1) includes forming at least onecircumferential recess to have a cross section, as seen on a planecontaining the axis of the pipe section, which is butterfly shaped withits thinnest section midway between the two edges of the recess andthicker sections adjacent each edge of the recess.
 8. A method of layingand assembling sections of pipe into an indefinite length of pipingwhich comprises the steps of:(1) positioning an inner pipe section andan outer pipe section in general longitudinal alignment in a trenchbelow ground level for joining by telescoping the two sections togetherwith the two sections when joined having aligned circimferentialrecesses in their facing surfaces adjacent the telescoping ends andforming a ring passageway with the inner section having a pair ofcircumferential grooves spaced on opposite ends of its recess; (2)placing two spaced ring sealing gaskets around the inner sectionrespectively in the pair of grooves; (3) telescoping the inner sectionwith the two gaskets in the pair of grooves into the outer section to apredetermined position; (4) attaching two elongated conduits to the ringpassageway by two respective passages extending laterally through theouter section at generally vertical diametrically opposed positions; (5)covering the joined pipe sections with earth and allowing the sectionsto settle; (6) thereafter introducing a solidifiable fluid grout fromabove the trench through the conduit attached to the lower passage untilthe ring passageway is filled with grout; and (7) allowing the grout tosolidify.
 9. The method of claim 8 further comprising the step of(8)pressurizing the spaced between the sealed gaskets by closing oneconduit and introducing a fluid under superatmospheric pressure into theother conduit to test the sealing capabilities of the gaskets in theassembled joint; wherein step (8) is accomplished between steps (5) and(6).
 10. The method of claim 8 further comprising the step of(8)pressurizing the space between the sealing gaskets by closing oneconduit and introducing a fluid under superatmospheric pressure into theother conduit to test the sealing capabilities of the gaskets in theassembled joint; wherein step (8) is accomplished between steps (4) and(5).
 11. The method of claim 8 wherein step (6) additionally includesapplying a vacuum to the conduit attached to the upper passageway whilefluid grout is introduced through the lower passageway to inhibit airbubble formation with the grout.
 12. The method of claim 8 wherein step(4) includes extending the conduits from the outer pipe section to aboveground level.
 13. The method of claim 8 wherein step (2) includescoating the sealing gaskets and the inside surface of the bell sectionwith a lubricant.
 14. The method of claim 8 wherein step (1) includesforming the edges of the recesses at an angle with respect to theadjacent inside or outside surface of the respective outer and innersections.
 15. The method of claim 8 wherein step (1) includes forming atleast one circumferential recess to have a cross section, as seen on aplane containing the axis of the pipe section, which is wedge shapedwith its thickest dimension adjacent the end of the inner section andits thinnest dimension adjacent the end of the outer section.
 16. Themethod of claim 8 wherein step (1) includes forming at least onecircumferential recess to have a cross section, as seen on a planecontaining the axis of the pipe section, which is butterfly shaped withits thinnest section midway between the two edges of such recess andthicker sections adjacent each edge of such recess.
 17. A method oflaying, testing, and assembling sections of pipe into an indefinitelength of piping which comprises the steps of:(1) positioning an innerpipe section and an outer pipe section in general longitudinal alignmentin a trench below ground level for joining by telescoping the twosections together with the two sections when joined having alignedcircumferential recesses in their facing surfaces adjacent thetelescoping ends and forming a ring passageway with the inner sectionhaving a pair of circumferential grooves spaced on opposite ends of itsrecess; (2) placing the two spaced ring sealing gaskets around the innersection respectively in the pair of grooves; (3) telescoping the innersection with the two gaskets in the pair of grooves into the outersection to a predetermined depth; (4) attaching two elongated conduitsto the ring passageway by two respective passages extending laterallythrough the outer section at generally vertically diametrically opposedpositions; (5) pressurizing the space between the sealing gaskets byclosing one conduit and introducing a fluid under superatmosphericpressure into the other conduit to test the sealing capabilities of thegaskets in the assembled joint; (6) covering the joined pipe sectionswith earth and alowing the sections to settle; (7) thereafterintroducing a solidifiable fluid grout from above the trench through theconduit attached to the lower passage until the ring passageway isfilled with grout; (8) burying below ground level the upper ends of anyremainder of the two conduits; and (9) allowing the grout to solidify.18. The method of claim 17 wherein step (7) additionally includes thesteps of (10) applying a vacuum to the conduit attached to the upperpassageway while fluid is introduced through the lower passageway toinhibit air bubble formation with the grout.
 19. The method of claim 17further comprising the step of (10) repressurizing the space between thesealing gaskets by closing one conduit and introducing a fluid undersuperatmospheric pressure into the other conduit to test the sealingcapabilities of the gaskets in the assembled joint after step (6) andbefore step (7).
 20. The method of claim 17 wherein step (1) includesthe step of (10) forming at least one edge of the inside surface of theouter section at an angle to create a solidified grout wedge to inhibitlongitudinal decoupling movement between the outer and inner sectionswhile the solidified grout in two passages inhibit relative rotationbetween the outer and inner sections.